Combat veterans suffering from PTSD report problems with hostility and anger. Indeed, hostility in the form of irritability and anger outbursts are one of the DSM-III-R criteria for PTSD. However, although previous research has indicated that veterans with combat-related PTSD report more hostility and anger, they have not behaviorally demonstrated more hostility in laboratory settings. Behavioral demonstrations of interpersonal hostility are an important area of study because behavioral hostility is a more reliable, objective measure of hostility, and has been more strongly associated with disease outcomes than self-report measures of hostility. In addition, comprehensive empirical assessment of hostility in Vietnam combat-related PTSD veterans is lacking. Our pilot data is the first documentation that PTSD combat veterans demonstrate more hostility during a structured interpersonal interaction. The first purpose of the proposed study is to collect multiple measures of hostility (behavioral, self-report, spouse-ratings and daily activity ratings) with 4 combat veterans groups in order to describe and compare both hostility levels and modes of expression associated with combat-related PTSD. Thirty veterans with combat-related PTSD, 30 psychiatrically-healthy, help- seeking combat veterans, 30 psychiatrically-healthy community (non-help-seeking) combat veterans and 30 combat veterans with major depression will be recruited. Major depression combat veterans have been chosen because irritability is a common associated feature of the disorder, and previous research has indicated that the level and mode of hostility in major depression patients is higher than non-psychiatric groups. In non-veteran populations, hostility has been prospectively associated with poorer health and mortality outcomes. However, the possible negative physical health effects of hostility in PTSD combat veterans has only recently begun to receive investigative attention. The second purpose of this study is to collect information on a range of health parameters on two occasions one year apart (including self-report of health problems, ambulatory monitoring of blood pressure and heart rate and lipid panel profiles). These data will be used to evaluate the prospective relationship of hostility to health parameters in Vietnam veterans with combat-related PTSD.